In cataract surgery, it is important to control intraocular infusion pressure. Irrigation solution is commonly used to maintain both the anatomic and physiologic integrity of intraocular tissues during surgery. In known irrigation systems, irrigation fluid is supplied in a bag or bottle that is suspended on a pole in a “neck-down” position, with a supply tube extending from the lowermost portion of the irrigation supply source. In the “neck-down” position, air remains at the top of the bag or bottle.
In some systems, gravity feed methods 10 or pressurized gas sources 20 are used for controlling surgical irrigation pressure and flow of the irrigation system. Gravity feed irrigations methods 10, such as those illustrated in FIG. 1; provide a pressure and flow based on the height of the supply source 12. The higher the supply source above the eye, the greater the pressure and flow. The lower the supply source, the lower the pressure and flow. The surgeon controls the supply source height by raising or lowering the pole to which the supply source is mounted. Gravity feed methods have limitations on pressure response rates due to the requirements of raising and lowering the irrigation bottle.
Pressurized gas sources 20, such as those illustrated in FIG. 2, control the irrigation pressure by increasing or decreasing the pressure inside an irrigation bottle 23. The bottle 23 is suspended at a constant height and a gas pressure pump is connected to the bottle 23 (e.g., through line 32). While pressurized gas methods improve on the pressure response rates from the gravity feed method, pressurized gas methods require cumbersome venting snorkel devices that complicate the surgical setup. Further, both methods require filtering of air or gas into the bottle to prevent contamination which adds cost and complexity.
Other pressurized irrigation systems have used compression, combined with gravity, to deliver irrigation fluid to the surgical site. In such systems, a compliant irrigation bag is squeezed, thereby pushing the irrigation fluid into the system. However, in such systems, the squeezing action causes the bag volume and the geometry to change, which can change the neck position during use. Such changes can cause problems with the neck, associated tubing, and the pressurized system as a whole, because the neck may become trapped or pinched within the squeezing system.
Moreover, because prior art systems have the irrigation supply container oriented in a “neck-down” position, air is trapped at the top of the irrigation container. Thus, prior to use in surgery, the fluid management components, including the irrigation container, need to be purged of air or primed. While the priming and diagnostic system procedure is effective, it is unable to remove all of the air from within the irrigation supply container. This residual entrained air has a deleterious effect on overall system performance. For example, air trapped in the irrigation supply container can slow down the fast hydraulic response necessary for optimum performance.
Accordingly, there exists a need for an improved mounting arrangement for a pressurized irrigation supply that improves operation by reducing potential problems that occur during operation of an infusion system.